Optical sensors are well known in the electronic sensing arts. Optical sensors are commonly used in the field of printers and hand-held and desktop computers. Functions of sensors within this field usually include label detection, gap detection, skew, label length or width determination, etc. Advantages of these devices include their small size and durability. As with any device, however, there are also disadvantages, including the fact that a certain level of sensitivity, precision or tolerance associated with each sensor, can vary greatly. Additionally, ambient lighting can greatly confuse the interpretation of the light received by the sensor, and the characteristics of the print media or other sensing media or sensing target can vary greatly. A higher sensitivity or tighter tolerance can result in a higher sensor cost, which presents another disadvantage.
In order to maintain reasonable costs associated with devices, such as, for example, printers, while attaining considerable accuracy, conventional sensing devices have employed a variety of sensing methods, which utilize lower-cost sensors to achieve acceptable results. Such sensors, however, generally become dirty, decay over time, rely upon inconsistent and varying manufacturing techniques, and in many other manners the characteristics of each sensor are different or can change over time. Thus, conventional sensor designs, which did not precisely account for these variations or changing ambient conditions, could not provide consistently reliable results. Other prior art designs offer manual adjustability or self-calibration but with heightened design and manufacturing complexity and greatly increased costs.
Optical sensors are ideally suited for edge detection. As explained, above, however, conventional optical sensors have a number of limitations, including the inability to provide highly accurate and repeatable sensing data regardless of the direction of motion of a sensor or optical light occlusion thereof.
The present inventors have thus concluded, based on the foregoing, that a need exists for an improved optical sensor, including methods and systems thereof, for use in detecting the edge of target objects. The present inventors believed that the improved optical sensing methods and systems disclosed herein can provide an accurate and repeatable edge detection of an object without suffering from the inconsistencies and inefficiencies that currently plague conventional optical sensing devices.